224 R EPORT OF THE No. 3 



Such information can be supplied by additional sketching, though experience 

 has shown that this class of work can be done to better advantage from a much 

 greater height than that used for mapping timber, since a distinction between 

 land and water surfaces is possible from practically any altitude. For the 

 same reasons it is often possible at this higher altitude — 10,000 feet if weather 

 conditions are suitable — to greatly expedite subsequent closer examination 

 of timbered areas at lower altitudes, by splitting the territory into two or three 

 general types, such as green timber, muskeg, barren, all of which can be recog- 

 nized at the above altitudes. 



Of the total flying time for the season, 342 hours, an analysis of the flight 

 records shows that over 90 per cent, was given to sketching forest types and 

 topography, the remainder being taken up with transportation of ground 

 parties and photography. 



(b) Indirect Mapping. — While it is realized that photography can produce 

 results which sketch work cannot hope to replace, it was not used in the past 

 season as an essential part of type mapping. So far no photographic system 

 has been developed which could produce the information desired at a cost which 

 the nature of the work would justify. Undoubtedly photography will eventually 

 go much further in this direction than at present. But while the carrying of 

 timber type lines over immense areas by photography is still very expensive, 

 it is considered that in its present state of development it can be used to advan- 

 tage to give information for the construction of base maps for sketching which 

 would render the work more accurate and would also effect an economy in the 

 whole operation, since a very small saving in flying time will pay for a great 

 deal of photographic work. 



Procedure for type mapping in the past season's work may therefore be 

 summarized as follows: — Type maps were prepared by an experienced forest 

 observer, sketching directly on base maps two miles to the inch scale. In all 

 13,500 square miles or 8,640,000 acres were thus mapped, requiring flights totalling 

 25,000 air miles. Information from these maps prepared in flight was then, on 

 returning to the base at Remi Lake, transferred to an office map, and from the 

 latter information as to timber was given to the ground parties in map form 

 from time to time as required. It might be well to state here as an indication 

 of the accuracy of this work that information as to type limits given to and 

 checked by the ground parties was found to be reliable except in two instances; 

 (1) during the first three or four flights the difference between dense stands of 

 scrubby dwarf spruce and merchantable stands of the same species, while recog- 

 nized, was not known to indicate such significant differences in the stand as 

 actually existed. Ground study by the observers, as mentioned above, settled 

 this question so that throughout the remainder of the season no trouble was 

 experienced in this connection, (2) there was throughout the season a tendency 

 to overestimate the percentage of hardwoods associated with the conifers in 

 the mixed type. 



2. Ground Work. 



After the area had been typed and mapped from the air, a copy of this 

 map was delivered to the ground parties, who then were in a position to locate 

 starting points for samples for the estimate. The strip method was adopted, 

 and was confined to areas bearing commercial quantities. 



Fifteen men were used on the Abitibi and Mattagami rivers, one chief, 

 two sub-chiefs, six other forestry men, four canoe men and packers and two 

 cooks. The whole party with seven canoes, seventeen and eighteen foot "Chest- 



